|
| gen_except.sa 3.7 1/16/92
|
| gen_except --- FPSP routine to detect reportable exceptions
|
| This routine compares the exception enable byte of the
| user_fpcr on the stack with the exception status byte
| of the user_fpsr.
|
| Any routine which may report an exceptions must load
| the stack frame in memory with the exceptional operand(s).
|
| Priority for exceptions is:
|
| Highest: bsun
| snan
| operr
| ovfl
| unfl
| dz
| inex2
| Lowest: inex1
|
| Note: The IEEE standard specifies that inex2 is to be
| reported if ovfl occurs and the ovfl enable bit is not
| set but the inex2 enable bit is.
|
|
| Copyright (C) Motorola, Inc. 1990
| All Rights Reserved
|
| For details on the license for this file, please see the
| file, README, in this same directory.
GEN_EXCEPT: |idnt 2,1 | Motorola 040 Floating Point Software Package
|section 8
#include "fpsp.h"
|xref real_trace
|xref fpsp_done
|xref fpsp_fmt_error
exc_tbl:
.long bsun_exc
.long commonE1
.long commonE1
.long ovfl_unfl
.long ovfl_unfl
.long commonE1
.long commonE3
.long commonE3
.long no_match
.global gen_except
gen_except:
cmpib #IDLE_SIZE-4,1(%a7) |test for idle frame
beq do_check |go handle idle frame
cmpib #UNIMP_40_SIZE-4,1(%a7) |test for orig unimp frame
beqs unimp_x |go handle unimp frame
cmpib #UNIMP_41_SIZE-4,1(%a7) |test for rev unimp frame
beqs unimp_x |go handle unimp frame
cmpib #BUSY_SIZE-4,1(%a7) |if size <> $60, fmt error
bnel fpsp_fmt_error
leal BUSY_SIZE+LOCAL_SIZE(%a7),%a1 |init a1 so fpsp.h
| ;equates will work
| Fix up the new busy frame with entries from the unimp frame
|
movel ETEMP_EX(%a6),ETEMP_EX(%a1) |copy etemp from unimp
movel ETEMP_HI(%a6),ETEMP_HI(%a1) |frame to busy frame
movel ETEMP_LO(%a6),ETEMP_LO(%a1)
movel CMDREG1B(%a6),CMDREG1B(%a1) |set inst in frame to unimp
movel CMDREG1B(%a6),%d0 |fix cmd1b to make it
andl #0x03c30000,%d0 |work for cmd3b
bfextu CMDREG1B(%a6){#13:#1},%d1 |extract bit 2
lsll #5,%d1
swap %d1
orl %d1,%d0 |put it in the right place
bfextu CMDREG1B(%a6){#10:#3},%d1 |extract bit 3,4,5
lsll #2,%d1
swap %d1
orl %d1,%d0 |put them in the right place
movel %d0,CMDREG3B(%a1) |in the busy frame
|
| Or in the FPSR from the emulation with the USER_FPSR on the stack.
|
fmovel %FPSR,%d0
orl %d0,USER_FPSR(%a6)
movel USER_FPSR(%a6),FPSR_SHADOW(%a1) |set exc bits
orl #sx_mask,E_BYTE(%a1)
bra do_clean
|
| Frame is an unimp frame possible resulting from an fmove <ea>,fp0
| that caused an exception
|
| a1 is modified to point into the new frame allowing fpsp equates
| to be valid.
|
unimp_x:
cmpib #UNIMP_40_SIZE-4,1(%a7) |test for orig unimp frame
bnes test_rev
leal UNIMP_40_SIZE+LOCAL_SIZE(%a7),%a1
bras unimp_con
test_rev:
cmpib #UNIMP_41_SIZE-4,1(%a7) |test for rev unimp frame
bnel fpsp_fmt_error |if not $28 or $30
leal UNIMP_41_SIZE+LOCAL_SIZE(%a7),%a1
unimp_con:
|
| Fix up the new unimp frame with entries from the old unimp frame
|
movel CMDREG1B(%a6),CMDREG1B(%a1) |set inst in frame to unimp
|
| Or in the FPSR from the emulation with the USER_FPSR on the stack.
|
fmovel %FPSR,%d0
orl %d0,USER_FPSR(%a6)
bra do_clean
|
| Frame is idle, so check for exceptions reported through
| USER_FPSR and set the unimp frame accordingly.
| A7 must be incremented to the point before the
| idle fsave vector to the unimp vector.
|
do_check:
addl #4,%a7 |point A7 back to unimp frame
|
| Or in the FPSR from the emulation with the USER_FPSR on the stack.
|
fmovel %FPSR,%d0
orl %d0,USER_FPSR(%a6)
|
| On a busy frame, we must clear the nmnexc bits.
|
cmpib #BUSY_SIZE-4,1(%a7) |check frame type
bnes check_fr |if busy, clr nmnexc
clrw NMNEXC(%a6) |clr nmnexc & nmcexc
btstb #5,CMDREG1B(%a6) |test for fmove out
bnes frame_com
movel USER_FPSR(%a6),FPSR_SHADOW(%a6) |set exc bits
orl #sx_mask,E_BYTE(%a6)
bras frame_com
check_fr:
cmpb #UNIMP_40_SIZE-4,1(%a7)
beqs frame_com
clrw NMNEXC(%a6)
frame_com:
moveb FPCR_ENABLE(%a6),%d0 |get fpcr enable byte
andb FPSR_EXCEPT(%a6),%d0 |and in the fpsr exc byte
bfffo %d0{#24:#8},%d1 |test for first set bit
leal exc_tbl,%a0 |load jmp table address
subib #24,%d1 |normalize bit offset to 0-8
movel (%a0,%d1.w*4),%a0 |load routine address based
| ;based on first enabled exc
jmp (%a0) |jump to routine
|
| Bsun is not possible in unimp or unsupp
|
bsun_exc:
bra do_clean
|
| The typical work to be done to the unimp frame to report an
| exception is to set the E1/E3 byte and clr the U flag.
| commonE1 does this for E1 exceptions, which are snan,
| operr, and dz. commonE3 does this for E3 exceptions, which
| are inex2 and inex1, and also clears the E1 exception bit
| left over from the unimp exception.
|
commonE1:
bsetb #E1,E_BYTE(%a6) |set E1 flag
bra commonE |go clean and exit
commonE3:
tstb UFLG_TMP(%a6) |test flag for unsup/unimp state
bnes unsE3
uniE3:
bsetb #E3,E_BYTE(%a6) |set E3 flag
bclrb #E1,E_BYTE(%a6) |clr E1 from unimp
bra commonE
unsE3:
tstb RES_FLG(%a6)
bnes unsE3_0
unsE3_1:
bsetb #E3,E_BYTE(%a6) |set E3 flag
unsE3_0:
bclrb #E1,E_BYTE(%a6) |clr E1 flag
movel CMDREG1B(%a6),%d0
andl #0x03c30000,%d0 |work for cmd3b
bfextu CMDREG1B(%a6){#13:#1},%d1 |extract bit 2
lsll #5,%d1
swap %d1
orl %d1,%d0 |put it in the right place
bfextu CMDREG1B(%a6){#10:#3},%d1 |extract bit 3,4,5
lsll #2,%d1
swap %d1
orl %d1,%d0 |put them in the right place
movel %d0,CMDREG3B(%a6) |in the busy frame
commonE:
bclrb #UFLAG,T_BYTE(%a6) |clr U flag from unimp
bra do_clean |go clean and exit
|
| No bits in the enable byte match existing exceptions. Check for
| the case of the ovfl exc without the ovfl enabled, but with
| inex2 enabled.
|
no_match:
btstb #inex2_bit,FPCR_ENABLE(%a6) |check for ovfl/inex2 case
beqs no_exc |if clear, exit
btstb #ovfl_bit,FPSR_EXCEPT(%a6) |now check ovfl
beqs no_exc |if clear, exit
bras ovfl_unfl |go to unfl_ovfl to determine if
| ;it is an unsupp or unimp exc
| No exceptions are to be reported. If the instruction was
| unimplemented, no FPU restore is necessary. If it was
| unsupported, we must perform the restore.
no_exc:
tstb UFLG_TMP(%a6) |test flag for unsupp/unimp state
beqs uni_no_exc
uns_no_exc:
tstb RES_FLG(%a6) |check if frestore is needed
bne do_clean |if clear, no frestore needed
uni_no_exc:
moveml USER_DA(%a6),%d0-%d1/%a0-%a1
fmovemx USER_FP0(%a6),%fp0-%fp3
fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
unlk %a6
bra finish_up
|
| Unsupported Data Type Handler:
| Ovfl:
| An fmoveout that results in an overflow is reported this way.
| Unfl:
| An fmoveout that results in an underflow is reported this way.
|
| Unimplemented Instruction Handler:
| Ovfl:
| Only scosh, setox, ssinh, stwotox, and scale can set overflow in
| this manner.
| Unfl:
| Stwotox, setox, and scale can set underflow in this manner.
| Any of the other Library Routines such that f(x)=x in which
| x is an extended denorm can report an underflow exception.
| It is the responsibility of the exception-causing exception
| to make sure that WBTEMP is correct.
|
| The exceptional operand is in FP_SCR1.
|
ovfl_unfl:
tstb UFLG_TMP(%a6) |test flag for unsupp/unimp state
beqs ofuf_con
|
| The caller was from an unsupported data type trap. Test if the
| caller set CU_ONLY. If so, the exceptional operand is expected in
| FPTEMP, rather than WBTEMP.
|
tstb CU_ONLY(%a6) |test if inst is cu-only
beq unsE3
| move.w #$fe,CU_SAVEPC(%a6)
clrb CU_SAVEPC(%a6)
bsetb #E1,E_BYTE(%a6) |set E1 exception flag
movew ETEMP_EX(%a6),FPTEMP_EX(%a6)
movel ETEMP_HI(%a6),FPTEMP_HI(%a6)
movel ETEMP_LO(%a6),FPTEMP_LO(%a6)
bsetb #fptemp15_bit,DTAG(%a6) |set fpte15
bclrb #UFLAG,T_BYTE(%a6) |clr U flag from unimp
bra do_clean |go clean and exit
ofuf_con:
moveb (%a7),VER_TMP(%a6) |save version number
cmpib #BUSY_SIZE-4,1(%a7) |check for busy frame
beqs busy_fr |if unimp, grow to busy
cmpib #VER_40,(%a7) |test for orig unimp frame
bnes try_41 |if not, test for rev frame
moveql #13,%d0 |need to zero 14 lwords
bras ofuf_fin
try_41:
cmpib #VER_41,(%a7) |test for rev unimp frame
bnel fpsp_fmt_error |if neither, exit with error
moveql #11,%d0 |need to zero 12 lwords
ofuf_fin:
clrl (%a7)
loop1:
clrl -(%a7) |clear and dec a7
dbra %d0,loop1
moveb VER_TMP(%a6),(%a7)
moveb #BUSY_SIZE-4,1(%a7) |write busy fmt word.
busy_fr:
movel FP_SCR1(%a6),WBTEMP_EX(%a6) |write
movel FP_SCR1+4(%a6),WBTEMP_HI(%a6) |exceptional op to
movel FP_SCR1+8(%a6),WBTEMP_LO(%a6) |wbtemp
bsetb #E3,E_BYTE(%a6) |set E3 flag
bclrb #E1,E_BYTE(%a6) |make sure E1 is clear
bclrb #UFLAG,T_BYTE(%a6) |clr U flag
movel USER_FPSR(%a6),FPSR_SHADOW(%a6)
orl #sx_mask,E_BYTE(%a6)
movel CMDREG1B(%a6),%d0 |fix cmd1b to make it
andl #0x03c30000,%d0 |work for cmd3b
bfextu CMDREG1B(%a6){#13:#1},%d1 |extract bit 2
lsll #5,%d1
swap %d1
orl %d1,%d0 |put it in the right place
bfextu CMDREG1B(%a6){#10:#3},%d1 |extract bit 3,4,5
lsll #2,%d1
swap %d1
orl %d1,%d0 |put them in the right place
movel %d0,CMDREG3B(%a6) |in the busy frame
|
| Check if the frame to be restored is busy or unimp.
|** NOTE *** Bug fix for errata (0d43b #3)
| If the frame is unimp, we must create a busy frame to
| fix the bug with the nmnexc bits in cases in which they
| are set by a previous instruction and not cleared by
| the save. The frame will be unimp only if the final
| instruction in an emulation routine caused the exception
| by doing an fmove <ea>,fp0. The exception operand, in
| internal format, is in fptemp.
|
do_clean:
cmpib #UNIMP_40_SIZE-4,1(%a7)
bnes do_con
moveql #13,%d0 |in orig, need to zero 14 lwords
bras do_build
do_con:
cmpib #UNIMP_41_SIZE-4,1(%a7)
bnes do_restore |frame must be busy
moveql #11,%d0 |in rev, need to zero 12 lwords
do_build:
moveb (%a7),VER_TMP(%a6)
clrl (%a7)
loop2:
clrl -(%a7) |clear and dec a7
dbra %d0,loop2
|
| Use a1 as pointer into new frame. a6 is not correct if an unimp or
| busy frame was created as the result of an exception on the final
| instruction of an emulation routine.
|
| We need to set the nmcexc bits if the exception is E1. Otherwise,
| the exc taken will be inex2.
|
leal BUSY_SIZE+LOCAL_SIZE(%a7),%a1 |init a1 for new frame
moveb VER_TMP(%a6),(%a7) |write busy fmt word
moveb #BUSY_SIZE-4,1(%a7)
movel FP_SCR1(%a6),WBTEMP_EX(%a1) |write
movel FP_SCR1+4(%a6),WBTEMP_HI(%a1) |exceptional op to
movel FP_SCR1+8(%a6),WBTEMP_LO(%a1) |wbtemp
| btst.b #E1,E_BYTE(%a1)
| beq.b do_restore
bfextu USER_FPSR(%a6){#17:#4},%d0 |get snan/operr/ovfl/unfl bits
bfins %d0,NMCEXC(%a1){#4:#4} |and insert them in nmcexc
movel USER_FPSR(%a6),FPSR_SHADOW(%a1) |set exc bits
orl #sx_mask,E_BYTE(%a1)
do_restore:
moveml USER_DA(%a6),%d0-%d1/%a0-%a1
fmovemx USER_FP0(%a6),%fp0-%fp3
fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
frestore (%a7)+
tstb RES_FLG(%a6) |RES_FLG indicates a "continuation" frame
beq cont
bsr bug1384
cont:
unlk %a6
|
| If trace mode enabled, then go to trace handler. This handler
| cannot have any fp instructions. If there are fp inst's and an
| exception has been restored into the machine then the exception
| will occur upon execution of the fp inst. This is not desirable
| in the kernel (supervisor mode). See MC68040 manual Section 9.3.8.
|
finish_up:
btstb #7,(%a7) |test T1 in SR
bnes g_trace
btstb #6,(%a7) |test T0 in SR
bnes g_trace
bral fpsp_done
|
| Change integer stack to look like trace stack
| The address of the instruction that caused the
| exception is already in the integer stack (is
| the same as the saved friar)
|
| If the current frame is already a 6-word stack then all
| that needs to be done is to change the vector# to TRACE.
| If the frame is only a 4-word stack (meaning we got here
| on an Unsupported data type exception), then we need to grow
| the stack an extra 2 words and get the FPIAR from the FPU.
|
g_trace:
bftst EXC_VEC-4(%sp){#0:#4}
bne g_easy
subw #4,%sp | make room
movel 4(%sp),(%sp)
movel 8(%sp),4(%sp)
subw #BUSY_SIZE,%sp
fsave (%sp)
fmovel %fpiar,BUSY_SIZE+EXC_EA-4(%sp)
frestore (%sp)
addw #BUSY_SIZE,%sp
g_easy:
movew #TRACE_VEC,EXC_VEC-4(%a7)
bral real_trace
|
| This is a work-around for hardware bug 1384.
|
bug1384:
link %a5,#0
fsave -(%sp)
cmpib #0x41,(%sp) | check for correct frame
beq frame_41
bgt nofix | if more advanced mask, do nada
frame_40:
tstb 1(%sp) | check to see if idle
bne notidle
idle40:
clrl (%sp) | get rid of old fsave frame
movel %d1,USER_D1(%a6) | save d1
movew #8,%d1 | place unimp frame instead
loop40: clrl -(%sp)
dbra %d1,loop40
movel USER_D1(%a6),%d1 | restore d1
movel #0x40280000,-(%sp)
frestore (%sp)+
unlk %a5
rts
frame_41:
tstb 1(%sp) | check to see if idle
bne notidle
idle41:
clrl (%sp) | get rid of old fsave frame
movel %d1,USER_D1(%a6) | save d1
movew #10,%d1 | place unimp frame instead
loop41: clrl -(%sp)
dbra %d1,loop41
movel USER_D1(%a6),%d1 | restore d1
movel #0x41300000,-(%sp)
frestore (%sp)+
unlk %a5
rts
notidle:
bclrb #etemp15_bit,-40(%a5)
frestore (%sp)+
unlk %a5
rts
nofix:
frestore (%sp)+
unlk %a5
rts
|end